Flexible rubber gaiters are used in motor cars to protect constant velocity joints so as to prevent ingress of dirt and moisture and egress of lubricants. These gaiters customarily comprise moulded tubes having cylindrical end portions suitably diametered to fit the pertaining joint members and a flexible convoluted central portion. The end portions are clamped to the joint members by straps located in seating channels in the rubber gaiter.
UK Patent No. 2156452 discloses a moulded rubber gaiter of this kind further having end portions adapted by the provision of multiple fitting sections of different diameters allowing attachment to a number of different dimensions of joint members. This provides a versatile `universal` gaiter which can be used with constant velocity joints of different motor car models by appropriate cutting away of unwanted outer zones of the fitting sections. The requisite flexibility of the gaiter is derived essentially from the central portion which may be a bellows type construction and the end portions are of limited flexibility. Whilst this arrangement is generally satisfactory, in the case where the gaiter is used with an appreciable number of remaining inner ones of the fitting sections, these remaining fitting sections impose limitations on the overall flexibility of the gaiter because the fitting sections incorporate relatively rigid seating channels for the fixing straps. This is especially problematical at the wider diameter end of the gaiter where, in use, there is considerable axial flexing as the joint members rotate and pivot relative to each other (as is the case with constant velocity joints).
With the aim of improving flexibility at the wider end portion, GB 2232729 proposes inwardly curved fitting sections with outwardly curved folds between these sections. With this arrangement, the flexibility of the wider end portion of the gaiter is enhanced by the outwardly curved folds and also by the unused curved fitting sections which act as further folds.
This arrangement has considerable advantages. However, the provision of curved folds between the fitting sections adds to the length and bulk of the gaiter thereby requiring an increased amount of material. Also, the use of flexible inner and outer curved folds at the wider end of the gaiter can give rise to collapsing of the fold structure and consequent restriction of flexibility and increased wear.
In the latter respect, where the movement of the gaiter in use involves rotation about its axis and also pivoting or flexing at a position along the axis at the wider end of the gaiter, this has the effect of bending the folds at the wider end of the gaiter at one side, in the manner of a hinge joint and this can cause collapse of the folds rather than smooth pivoting. The folds thereby become flattened or crumpled.